In a manufacturing process of a semiconductor device, the diameter of a semiconductor substrate such as a silicon wafer or a compound semiconductor wafer has been increased and the thickness thereof is being reduced. A semiconductor substrate having a large diameter and a small thickness may be bent or cracked at the time of conveyance or a polishing process. Therefore, after reinforcing the semiconductor substrate by bonding a supporting substrate thereto, the conveyance or polishing process is performed, and then the supporting substrate is peeled off from the semiconductor substrate.
For example, Japanese Laid-Open Patent Publication No. 2013-149655 discloses a method which adsorbs and holds a semiconductor substrate by a first holding unit and moves the outer periphery of a second holding unit in a vertical direction while maintaining an adsorbed and supported state of the supporting substrate by the second holding unit to peel off the supporting substrate from the semiconductor substrate.